Embodiments of the present invention relate to a protocol tester for performing a protocol test, said protocol tester exhibiting an input for the feeding in of data, a protocol decoding device for the decoding of data, and an output for providing the decoded data. They also relate to a corresponding method for performing a protocol test.
Preparations by the mobile radio industry for the transition to 3G are increasingly taking shape. UMTS and CDMA2000 are third generation (3G) technologies that have emerged as a result of the demand for more mobile bandwidth and new services, and, with these characteristics, have the potential for opening up new sources of income. The new 3G network elements, interfaces and protocols will pose new challenges for installation technicians and network operators. In contrast to the 2G technology, where standards are well known and consolidated, interoperability problems can often no longer be resolved with existing protocol monitors.
With the introduction of 3G, new elements have to be installed practically everywhere in the network—probably by different providers. Equipment developers interpret the new 3G specifications and standards in good faith, yet there will inevitably be different solutions and diverging implementations between the manufacturers. The result will be compatibility problems, e.g. when a new Radio Network Controller (RNC) or Base Station Controller (BSC) of supplier A is connected to an Mobile Switching Center (MSC) of supplier B. Until 3G interoperability between different manufactures is well established and understood in all aspects, a check, start-up, error diagnosis and acceptance will be more complicated than ever. Furthermore, future standards and protocols will likely introduce new, but similar interoperability issues. According to the prior art, the protocol test methods used in this process can be subdivided into three main categories:
Monitoring: This is the simplest method of protocol testing. It is a proven means for many protocol and interoperability problems, particularly in established 2G networks. A protocol monitor is usually not intrusive; it records messages, decodes them and displays them in a readable form. A monitor can draw attention to signaling errors, but it cannot interpret the recorded parameters and values in their specific context, i.e. specify the cause of the error. Monitoring tools are available as compact, low-priced configurations for local use.
Simulation and emulation: A protocol simulator/emulator assumes the function of a network element and is therefore considered an intrusive measuring tool. Depending on the configuration it can, just like the missing element, generate protocol messages and respond to messages received. Simulators/emulators are more complex to configure, but some apparatuses dispose of aids with which the test configurations can be defined in a simple manner. Until now protocol simulators/emulators have been more complex, expensive and bigger than monitoring tools. This, however, has changed drastically with the most recent trends.
Conformity test: This is the performing of pass/fail tests with predefined test cases. A conformity test is often used for the acceptance of newly installed network elements and requires a simulator/emulator.
As already mentioned, it will most likely be inevitable for 2.5 and 3G installations to check the interoperability between elements of different apparatus manufacturers. The interfaces between the network elements are mostly “open”. This means that a network operator can, for example, procure an MSC from one supplier and the BSC/ Base Transceiver Station (BTS) pair or the RNC from a second supplier. On the one hand, this promotes healthy competition, but, on the other hand, it also complicates the installation and testing process.
Apart form the interoperability problem explained above, the next question is how the two local providers should be coordinated. Only rarely do two installation teams—one for the MSC and one for the BSC/BTS or RNC—work side by side and perform their task simultaneously. What occurs far more frequently is that one team finishes its work some days or even weeks before the other and wants to bring the order to a conclusion with an acceptance test that should occur as quickly as possible.
But how is the supplier of the BSC/BTS or RNC to prove the conformity and interoperability of its installation without an MSC? For this one needs a replacement MSC—a test apparatus that behaves like a real, fully conforming, functional MSC. Such a tool is, of course, the protocol simulator/emulator. It can take the place of the missing element, act together with the network, simulate flawed behavior, control the signaling and the message content and record the results of all of these processes. Thanks to the recent advancements in test and measurement technology, all these features can be integrated into a single compact apparatus for local use.
In summary, the persons dealing with the start-up of a network or the installation of new network components are thus confronted with tasks that are characterized by a high complexity and, what is more, have to be resolved under great time pressure, particularly locally.
Apart from the so-called protocol testers, whereby in the present application this term must be understood as comprising apparatuses for the purpose of monitoring, simulating, emulating and for performing conformity tests, there are known so-called BER (Bit Error Rate) testers. In this process, the bit error rate is a measure of the quality of the transmission on digital transmission paths of communication technology and network technology. Thus the bit error rate describes the ratio of the number of incorrectly transmitted bits in comparison to the total number of bits transmitted. For a measurement of the bit error rate there always has to exist a transmitter that generates a defined test pattern, and there has to be a receiver that evaluates this result and displays the result. In this process the measurement configuration can look very differently: if only one's own connection is examined, one works, for example, with a self-call. If, however, a complete transmission path has to be looked at, then an end-to-end measurement is carried out. In addition, both variants can work with loops, with the aid of which the test bit pattern is again sent back to the transmitter. In this case the transmitter and the receiver are one unit.